Originally built as a World War II casemated concrete coastal gun battery with two 16" MarkII-M1 guns mounted on M4 barbette carriages. This battery was a single level battery with the guns located on the same level as the central magazine. Each gun emplacement was casemated with heavy, reinforced concrete overhead protection and earth covering. The central magazine was built between and connecting the gun emplacements so that the powder and shells could be brought directly to the guns using overhead tracks and chain hoists. See 16" Rifle MarkII-M1.

Proof firing of the 16" guns on of Battery 108 on the East Reservation took place February-August 1943. A total of 15 rounds were fired in February and another 3 rounds in August.